OSCP SXPetSSc: Davidson Walkthrough & Solution

Hey guys! Today, we're diving deep into the OSCP SXPetSSc, focusing specifically on the Davidson machine. This box is a fantastic learning experience for anyone prepping for the OSCP exam or just looking to sharpen their penetration testing skills. We'll walk through each step, from initial enumeration to gaining root access. So, buckle up, and let's get started!

Initial Reconnaissance

Reconnaissance is the cornerstone of any successful penetration test. Before we even think about exploiting vulnerabilities, we need to gather as much information as possible about our target. For the Davidson box, this starts with basic network scanning. We'll use Nmap, the trusty sidekick of every pentester, to discover open ports and services running on the machine.

First, let's run a quick scan to identify open ports. I usually go for a SYN scan (-sS) to avoid making too much noise. We'll also enable version detection (-sV) to identify the services running on those ports. And, of course, we need to specify the target IP address. So, something like nmap -sS -sV 10.10.10.XXX would be our initial command.

Once the initial scan is complete, we'll analyze the results. Look for any interesting or unusual ports. Common ports like 22 (SSH), 80 (HTTP), and 443 (HTTPS) are always worth investigating. But also pay attention to less common ports, as they might be running custom applications or services that could be vulnerable.

Next, we'll perform a more aggressive scan to try and uncover additional information. This could involve using Nmap scripts (-sC) to enumerate services, identify potential vulnerabilities, and gather banner information. For example, a script like smb-enum-shares could be useful if we find port 445 (SMB) open. We might also try running Nikto against any web servers we find to identify potential web application vulnerabilities.

Remember, reconnaissance is an iterative process. As we gather more information, we'll refine our scans and focus on specific areas of interest. The goal is to build a comprehensive understanding of the target system before we start trying to exploit it. This thorough approach drastically increases our chances of success and ensures we don't miss any low-hanging fruit.

Web Application Analysis

Web application analysis is a critical step, especially when port 80 or 443 are open. Davidson, like many boxes, features a web application that serves as an entry point. We need to meticulously examine this application to understand its functionality and identify potential vulnerabilities.

Start by browsing the application manually. Click through all the links, explore all the features, and try to understand how the application works. Pay close attention to any input fields, forms, or areas where the application interacts with user-supplied data. These are often prime targets for exploitation.

Next, use a web proxy like Burp Suite to intercept and analyze the traffic between your browser and the web server. This allows you to see the HTTP requests and responses in detail, and to modify requests to test for vulnerabilities. Look for things like SQL injection, cross-site scripting (XSS), and command injection. These are common web application vulnerabilities that can be exploited to gain access to the system.

One technique is to fuzz the application by sending it unexpected or malformed data. This can sometimes reveal vulnerabilities that would not be apparent through normal use. For example, you could try entering long strings into input fields to test for buffer overflows, or sending special characters to see how the application handles them. Automation tools like ffuf and dirb can help automate finding hidden directories and files.

Directory brute-forcing using tools like dirbuster or gobuster to discover hidden directories and files. These directories may contain sensitive information, such as configuration files, backup files, or even vulnerable scripts. If you find any interesting files, download them and analyze them carefully. You might find hardcoded credentials, API keys, or other information that could be useful.

Always keep an eye out for potential file upload vulnerabilities. If the application allows users to upload files, try uploading malicious files, such as PHP scripts or reverse shells. If you can successfully upload and execute a malicious file, you can gain a foothold on the system. This is one of my go-to tests when I see an upload function!

Exploitation

Alright, the fun part, exploitation. Once we've identified a vulnerability, it's time to exploit it to gain access to the system. The specific exploitation techniques will vary depending on the vulnerability we've found, but the goal is always the same: to gain a foothold on the system.

If we've found a web application vulnerability, such as SQL injection or command injection, we can use it to execute arbitrary code on the server. This could involve injecting malicious SQL queries to extract data from the database, or injecting shell commands to execute system commands. Once we can execute code on the server, we can try to upload a reverse shell to gain interactive access.

A reverse shell is a program that connects back to our attacking machine, giving us a command-line interface on the target system. There are many different types of reverse shells, but one common option is a Python reverse shell. We can upload a Python script to the server and then execute it using our web application vulnerability. Once the script is running, it will connect back to our machine, giving us a shell.

After gaining a foothold on the system, our next goal is to escalate our privileges to root. This typically involves exploiting a vulnerability in the operating system or in a privileged application. There are many different techniques for privilege escalation, but some common options include exploiting kernel vulnerabilities, exploiting misconfigured services, and abusing SUID/SGID binaries.

SUID/SGID binaries are programs that run with the privileges of the owner or group, respectively. If a SUID/SGID binary is vulnerable, we can exploit it to gain root privileges. For example, if a SUID binary allows us to write to arbitrary files, we can use it to overwrite the /etc/passwd file and create a new root user. Or, we might discover a binary with elevated privileges that has a flaw, allowing us to inject commands. Tools like find / -perm -4000 -ls 2>/dev/null can help identify SUID binaries.

Privilege Escalation

Privilege escalation is the art of moving from a low-privileged user to a higher-privileged user, ideally root. This is often the most challenging part of a penetration test, but it's also one of the most rewarding. On Davidson, as with many OSCP-style boxes, it requires careful enumeration and a bit of lateral thinking.

Start by enumerating the system thoroughly. Check for any interesting files, directories, or processes that might be running with elevated privileges. Look for SUID/SGID binaries, as these can often be exploited to gain root access. Check for any misconfigured services or cron jobs that might be running as root.

Kernel exploits can be a reliable route, but they can also be risky and unstable. Before attempting to exploit a kernel vulnerability, make sure you have a good understanding of how the exploit works and what the potential consequences are. It's also a good idea to take a snapshot of the virtual machine before attempting a kernel exploit, so you can easily revert to a previous state if something goes wrong.

Linux capabilities are a more modern approach to privilege management that allows fine-grained control over the privileges of a process. Instead of running a process as root, you can grant it specific capabilities, such as the ability to bind to privileged ports or to change file ownership. If a process has unnecessary capabilities, it might be possible to exploit them to gain root access. The getcap command can be used to identify binaries with capabilities.

Another potential avenue for privilege escalation is exploiting vulnerabilities in third-party applications. Many systems have third-party applications installed that might be vulnerable to exploits. Keep your eyes peeled for programs that don't update frequently!

Post-Exploitation

After gaining root access, it's time for post-exploitation. This involves gathering information about the system, maintaining access, and covering our tracks. The specific post-exploitation steps will vary depending on the goals of the penetration test, but some common tasks include:

• Gathering sensitive data: This could include passwords, API keys, database credentials, or other information that could be used to compromise other systems.
• Maintaining access: This could involve installing a backdoor or creating a new user account with root privileges. This allows us to regain access to the system even if our initial exploit is patched.
• Covering our tracks: This could involve deleting logs, removing files, or modifying system configurations to make it harder to detect our presence. Keep in mind that the aim isn't always to be invisible. Sometimes the goal is to show what could be done. So, discuss with the client, what's the goal of the pentest.

Document everything you do during the post-exploitation phase. This will be important when writing the penetration test report. The report should include a detailed description of the vulnerabilities you found, the steps you took to exploit them, and the impact of the vulnerabilities on the system. It should also include recommendations for how to remediate the vulnerabilities and prevent them from being exploited in the future.

Tools like LinPEAS and AutoRecon can help you automate the enumeration and post-exploitation phases. These tools can quickly gather a lot of information about the system, which can save you a lot of time and effort. However, it's important to understand what these tools are doing and to verify their results. Don't just blindly trust the output of a tool without understanding what it means.

Conclusion

The Davidson box on OSCP SXPetSSc is a great way to practice your penetration testing skills and prepare for the OSCP exam. It requires a combination of reconnaissance, web application analysis, exploitation, and privilege escalation techniques. By following the steps outlined in this walkthrough, you should be able to successfully compromise the box and gain root access.

Remember, practice makes perfect. The more you practice, the better you'll become at penetration testing. So, keep practicing, keep learning, and keep hacking! Good luck, and have fun!